To date, transistors used in power electronic applications have typically been fabricated with silicon (Si) semiconductor materials. Common transistor devices for power applications include Si CoolMOS™, Si Power MOSFETs, and Si Insulated Gate Bipolar Transistors (IGBTs). Compound semiconductors, for example III-V compound semiconductors such as GaAs are also useful in some applications. More recently, silicon carbide (SiC) power devices have been considered. Group III-N semiconductor devices, such as gallium nitride (GaN) devices, are now emerging as attractive candidates to carry large currents, support high voltages and to provide very low on-resistance and fast switching times.